Microcalcifications are important diagnostic indicators in the mammographic screening of the breast. Currently, conventional x-ray mammography is the gold standard for the detection and diagnosis of microcalcifications. However, the efficacy of conventional mammography can be significantly reduced in the presence of dense breast parenchyma, which is found in approximately one in four women. Breast ultrasound is a powerful adjunct to mammography, but its role in the breast clinic is fundamentally limited by the inability of current ultrasound technology to reliably visualize microcalcifications. The improved visualization of microcalcifications with ultrasound would have a significant impact on the management of breast cancer by contributing diagnostic information in mammographically challenging cases and potentially reducing the number of unnecessary biopsies. Despite the rapid development of the state of the art of medical ultrasound, the optimization of ultrasound system design with regard to microcalcification visualization has not been investigated. The long term objective of the proposed research is to improve the visualization of microcalcifications in the breast with medical ultrasound. Using techniques that they have developed and implemented, the applicants proposed to conduct in excised tissue and in vivo studies to collect high quality ultrasound data from microcalcifications and breast tissue. These data will be used to characterize the backscatter properties of microcalcifications and breast tissue, to test the validity of the modeling of microcalcifications with the classical Faran model, to measure phase aberration in the breast, and to assess the relative impact of several physical factors on the visualization of microcalcifications. These factors will be speckle noise, spatial resolution, and phase aberration. Empirical and model results will be used to evaluate the relative efficacy of several proposed means to improve visualization, and to specify the ultrasound system performance criterion required to achieve reliable visualization. In vitro studies will also be undertaken to assess the potential of harmonic imaging techniques to improve microcalcification visualization. It is hypothesized that the optimization of system design parameters will improve the visualization of microcalcifications with ultrasound.